The present invention relates to colorants for keratin fibers, particularly human hair, containing 4-nitro-2,1,3-benzoxadiazole derivatives as dye.
As a rule, the color-changing treatment of keratin-containing fibers, for example human hair, wool or furs, is carried out by use of two dyeing methods. By the first method, the color is produced with oxidative or permanent colorants by use of a mixture of different developers and couplers and an oxidant. If necessary, to finish the coloring or to create special color effects, direct dyes may be added. The second method makes exclusive use of direct dyes which are applied to the fibers in a suitable carrier composition. This method is simple to use, quite mild and causes only minor damage to the keratin fibers. The direct dyes used for this purpose must meet numerous requirements. They must be toxicologically and dermatologically innocuous and must make it possible to achieve colorations of the desired intensity, which also assumes adequate water solubility, among other things. Moreover, the resulting colorations must be resistant to light, acids and rubbing.
The direct dyes for keratin fibers usually consist of a combination of different nonoxidative dyes. Because the choice of red and blue dyes that can be used in colorants for keratin fibers is limited, a need for such dyes continues to exist.
The object of the present invention is the use of 4-nitro-2,1,3-benzoxadiazole derivatives of general formula (I) as dye in colorants for keratin fibers, for example wool, silk, furs or hair, particularly human hair, 
wherein
X denotes oxygen, sulfur or NRa, Ra standing for hydrogen, a (C1-C4)-alkyl group, a monohydroxy-(C1-C4)-alkyl group, a polyhydroxy-(C2-C4)-alkyl group or a mono-(C1 C4)-alkoxy-(C1-C4)-alkyl group,
R1 and R2 can be equal or different and independently of each other denote hydrogen, a halogen atom (F, Cl, Br, I), a (C1-C4)-alkyl group, a halogen-substituted (C1-C4)-alkyl group, a (C1-C4)-alkoxy group, a nitro group or an NRbRc group, the Rb and Rc groups being equal or different and independently of each other denoting hydrogen, a (C1-C4)-alkyl group, an optionally substituted aromatic carbon ring or a (C1-C4)-alkanecarbonyl group, or Rb and Rc together with the nitrogen atom forming a heterocyclic (C3-C6) group (for example, an imidazolidino, piperidino, pyrrolidino, pyrazolidino, piperazino or morpholino group);
Q denotes hydrogen, an aliphatic group, an aromatic isocyclic group or an aromatic heterocyclic group, preferably an aromatic monocyclic to tetracyclic group, particularly an aromatic monocyclic or bicyclic group.
Preferred compounds of formula (I) are those wherein Q has the following meaning: methyl, ethyl, phenyl, biphenyl, C6H4R3, C6H3R3R4 or C6H2R3R4R5 wherein R3, R4 and R5 are equal or different and independently of each other stand for F, Cl, Br, I, CN, NO2, CF3, (C1-C4)-alkyl, (C1-C4)-alkoxy, monohydroxy-(C1-C4)-alkyl polyhydroxy-(C2-C4)-alkyl, mono-(C1-C4)-alkoxy-(C1-C4)-alkyl, (C1-C4)-alkylthio, hydroxy NRdRe, CHO, CORf, COOH, COORg, CONHRh or NHCORi, wherein Rd and Re independently of each other denote hydrogen, a (C1-C4)-alkyl group, a monohydroxy-C1-C4-alkyl group, a polyhydroxy-(C2-C4)-alkyl group or an optionally substituted aromatic carbon ring, and Rf, Rg, Rh and Ri independently of each other denote a (C1-C4)-alkyl group or an optionally substituted aromatic carbon ring.
Particularly preferred among the abovesaid compounds of formula (I) are those wherein: X stands for oxygen or NRa, with Ra denoting hydrogen, a (C1-C4)-alkyl group, a monohydroxy-(C1-C4)-alkyl group, a polyhydroxy-(C2-C4)-alkyl group or a mono-(C1-C4)-alkoxy-(C1-C4)-alkyl group;
R1=R2=hydrogen; Q stands for methyl, ethyl, phenyl, biphenyl, C6H4R3, C6H3R3R4 or C6H2R3R4R5, wherein R3, R4 and R5 are equal or different and independently of each other stand for F, Cl, Br, I, CN, NO2, CF3, (C1-C4)-alkyl, (C1-C4)-alkoxy, monohydroxy-(C1-C4)-alkyl, polyhydroxy-(C2-C4)-alkyl, mono-(C1-C4)-alkoxy-(C1-C4)-alkyl, (C1-C4)-alkylthio, hydroxy, NRdRe, CHO, CORf, COOH, COORg, CONHRh or NHCORl wherein Rd and Re independently of each other denote hydrogen, a (C1-C4)-alkyl group, a monohydroxy-(C1-C4)-alkyl group, a polyhydroxy-(C2-C4)-alkyl group or an optionally substituted aromatic carbon ring, and Rf, Rg, Rh and Ri independently of each other denote a (C1-C4)-alkyl group or an optionally substituted aromatic carbon ring.
Suitable 4-nitro-2,1,3-benzoxadiazole derivatives of formula (I) are, for example: 4-amino-7-nitro-2,1,3-benzoxadiazole; 4-N,N-dimethylamino-7-nitro-2,1,3-benzoxadiazole; 4-nitro-7-methoxy-2,1,3-benzoxadiazole; 4-nitro-7-ethoxy-2,1,3-benzoxadiazole; 4-nitro-7-phenoxy-2,1,3-benzoxadiazole; 4-nitro-7-(4xe2x80x2-nitrophenoxy)-2,1,3-benzoxadiazole; 4-nitro-7-(2xe2x80x2,4xe2x80x2,6xe2x80x2-trimethylphenoxy)-2,1,3-benzoxadiazole; 7-nitro-4-(N-phenylamino)-2,1,3-benzoxadiazole; 4-[N-1-(naphthalenyl)amino]-7-nitro-2,1,3-benzoxadiazole; 4-[N-(4xe2x80x2-chlorophenyl)amino]-7-nitro-2,1,3-benzoxadiazole; 4-[N-(4xe2x80x2-fluorophenyl)amino]-7-nitro-2,1,3-benzoxadiazole; 7-nitro-4-[N-(4xe2x80x2-nitrophenyl)amino]-2,1,3-benzoxadiazole; 7-nitro-4-[N-(3xe2x80x2-nitrophenyl)amino]-2,1,3-benzoxadiazole; 4-[N-(2xe2x80x2,4xe2x80x2-dinitrophenyl)amino]-7-nitro-2,1,3-benzoxadiazole; 4-[(7-nitro-2,1,3-benzoxadiazol-4-yl)amino]benzonitrile; 4-[N-(4xe2x80x2-methylphenyl)amino]-7-nitro-2,1,3-benzoxadiazole; 4-[N-(2xe2x80x2-methylphenyl)amino]-7-nitro-2,1,3-benzoxadiazole; 4-[N-(4xe2x80x2-methoxyphenyl)amino]-7-nitro-2,1,3-benzoxadiazole; 4-[(7-nitro-2,1,3-benzoxadiazol-4-yl)amino]phenol; 4-[(7-nitro-2,1,3-benzoxadiazol-4-yl)amino]-3-chloro-5-nitrophenol; 3-[(7-nitro-2,1,3-benzoxadiazol-4-yl)amino]phenol; 2-[(7-nitro-2,1,3-benzoxadiazol-4-yl)amino]phenol; N-(7-nitro-2,1,3-benzoxadiazol-4-yl)-1,4-diaminobenzene; N,N-dimethyl-Nxe2x80x2-(7-nitro-2,1,3-benzoxadiazol-4-yl)-1,4-diaminobenzene; N-(7-nitro-2,1,3-benzoxadiazol-4-yl)-2-(2xe2x80x2-hydroxyethyl)-1,4-diaminobenzene; N-(7-nitro-2,1,3-benzoxadiazol-4-yl)-2-(1xe2x80x2-hydroxyethyl)-1,4-diaminobenzene; N-(7-nitro-2,1,3-benzoxadiazol-4-yl)-2-methoxymethyl-1,4-diaminobenzene; N,N-di-(2xe2x80x2-hydroxyethyl)-Nxe2x80x2-(7-nitro-2,1,3-benzoxadiazol-4-yl)-2-nitro-1,4-diaminobenzene; methyl 4-[(7-nitro-2,1,3-benzoxadiazol-4-yl)amino]benzoate; 4-nitro-7-(phenylthio)-2,1,3-benzoxadiazole; 4-[(4xe2x80x2-chlorophenyl)thio]-7-nitro-2,1,3-benzoxadiazole; 4-[(3xe2x80x2-chlorophenyl)thio]-7-nitro-2,1,3-benzoxadiazole; 4-[(4xe2x80x2-bromophenyl)thio]-7-nitro-2,1,3-benzoxadiazole; 4-[(4xe2x80x2-methylphenyl)thio]-7-nitro-2,1,3-benzoxadiazole; 4-[(3xe2x80x2-methoxyphenyl)thio]-7-nitro-2,1,3-benzoxadiazole; 4-nitro-7-[(4xe2x80x2-nitrophenyl)thio]-2,1,3-benzoxadiazole; 2-[(7-nitro-2,1,3-benzoxadiazol-4-yl)thio]benzoic acid; 5,7-dinitro-N-phenyl-4-amino-2,1,3-benzoxadiazole; 4-{N-[(1,1xe2x80x2-biphenyl)-4-yl]amino}-5,7-dinitro-2,1,3-benzoxadiazole; 4-[N-(4xe2x80x2-chlorophenyl)amino]-5,7-dinitro-2,1,3-benzoxadiazole; 4-[N-(4xe2x80x2-bromophenyl)amino]-5,7-dinitro-2,1,3-benzoxadiazole; 4-[N-(3xe2x80x2-bromophenyl)amino]-5,7-dinitro-2,1,3-benzoxadiazole; 5,7-dinitro-4-[N-(4xe2x80x2-nitrophenyl)amino]-2,1,3-benzoxadiazole; 5,7-dinitro-4-[N-(3xe2x80x2-nitrophenyl)amino]-2,1,3-benzoxadiazole; 4-[N-(4xe2x80x2-methoxyphenyl)amino]-5,7-dinitro-2,1,3-benzoxadiazole; 4-[N-(4xe2x80x2-methylphenyl)amino]-5,7-dinitro-2,1,3-benzoxadiazole; Nxe2x80x2-(5,7-dinitro-2,1,3-benzoxadiazol-4-yl)-N,N-dimethyl-1,4-diaminobenzene; 3-[(5,7-dinitro-2,1,3-benzoxadiazol-4-yl)amino]phenol; 4-(N-methyl-N-phenylamino)-7-nitro-2,1,3-benzoxadiazole or 4-(N-ethyl-N-phenylamino)-7-nitro-2,1,3-benzoxadiazole and 4-[N-(2xe2x80x2-hydroxyethyl)-N-[4-di-(2xe2x80x2-hydroxyethyl)-2-nitrophenylamino]-7-nitro-2,1,3-benzoxadiazole.
The following among the aforesaid compounds of formula (I) are particularly preferred: 4-nitro-7-methoxy-2,1,3-benzoxadiazole; 4-nitro-7-ethoxy-2,1,3-benzoxadiazole; 4-nitro-7-phenoxy-2,1,3-benzoxadiazole; 7-nitro-4-(N-phenylamino)-2,1,3-benzoxadiazole; 4-[N-4xe2x80x2-methylphenyl)amino]-7-nitro-2,1,3-benzoxadiazole; 4-[N-4xe2x80x2-methoxyphenyl)amino]-7-nitro-2,1,3-benzoxadiazole; 4-[(7-nitro-2,1,3-benzoxadiazol-4-yl)amino]phenol; 3-[(7-nitro-2,1,3-benzoxadiazol-4-yl)amino]phenol; 2-[(7-nitro-2,1,3-benzoxadiazol-4-yl)amino]phenol; 4-[(7-nitro-2,1,3-benzoxadiazol-4-yl)amino]-3-chloro-5-nitrophenol; N-(7-nitro-2,1,3-benzoxadiazol-4-yl)-1,4-diaminobenzene; N-(7-nitro-2,1,3-benzoxadiazol-4-yl)-2-(2xe2x80x2-hydroxyethyl)-1,4-diaminobenzene; N-(7-nitro-2,1,3-benzoxadiazol-4-yl)-2-(1xe2x80x2-hydroxyethyl)-1,4-diaminobenzene; N-(7-nitro-2,1,3-benzoxadiazol-4-yl)-2-(methoxymethyl)-1,4-diaminobenzene; N,N-dimethyl-Nxe2x80x2-(7-nitro-2,1,3-benzoxadiazol-4-yl)-1,4-diaminobenzene; N,N-di-(2xe2x80x2-hydroxyethyl)-Nxe2x80x2-(7-nitro-2,1,3-benzoxadiazol-4-yl)-2-nitro-1,4-diaminobenzene and 4-(N-(2xe2x80x2-hydroxyethyl-N-[4-di-(2xe2x80x2-hydroxyethyl)-2-nitrophenylamino]-7-nitro-2,1,3-benzoxadiazole.
The 4-nitro-2,1,3-benzoxadiazole derivatives of formula (I) are usually employed in the form of a conventional colorant, the compound of formula (I) preferably being used in an amount from about 0.01 to about 10 wt. % and particularly from about 0.1 to about 8 wt. %.
Depending on the desired color shade, the colorant can optionally also contain, besides the dyes of formula (I), other known direct dyes from the group of anionic or cationic dyes, nitro dyes, azo dyes, anthraquinone dyes, triphenylmethane dyes or disperse dyes, it being possible to use said dyes individually or in admixture with each other.
In the colorants of the invention, the aforesaid direct dyes can be used in a total amount of about 0.01 to about 4 wt. %, the total amount of dyes in the colorant of the invention preferably being from about 0.01 to about 10 wt. % and particularly from about 0.1 to about 5 wt. %.
In addition, the colorants can contain all known and common additives for such preparations, for example perfume oils, complexing agents, waxes, preservatives, thickeners, alginates, guar gum, hair-care substances such as, for example, cationic polymers or lanolin derivatives, or anionic, nonionic, amphoteric or cationic surface-active substances. Preferably used are amphoteric or nonionic surface-active substances, for example betaine surfactants, propionates and glycinates such as, for example, cocoamphoglycinates or cocamphodiglycinates, ethoxylated surfactants with 1 to 1000 ethylene oxide units, preferably with 1 to 300 ethylene oxide units, for example glyceride alkoxylates, for example castor oil ethoxylated with 25 ethylene oxide units, polyglycolamides, ethoxylated alcohols and ethoxylated fatty alcohols (fatty alcohol alkoxylates) and ethoxylated fatty acid esters of sugars, particularly ethoxylated sorbitan fatty acid esters. The aforesaid constituents are used in amounts commonly employed for such purposes, for example the surface-active substances at a concentration from 0.1 to 30 wt. % and the hair-care agents in an amount from 0.1 to 5 wt. %.
Besides water, the colorants can also contain organic solvents, for example aliphatic or aromatic alcohols such as, for example, ethanol, isopropanol, 1,2-propanediol, 1-methoxypropan-2-ol, 1-ethoxypropan-2-ol, diethylene glycol monomethyl ether or diethylene glycol monoethyl ether, dipropylene glycol monomethyl ether, dipropylene glycol monoethyl ether, benzyl alcohol, benzyloxyethanol, phenylethyl alcohol, phenoxyethanol, cinnamyl alcohol and glycol ethers, particularly ethanol, isopropanol or benzyl alcohol. The water content is usually from about 25 to about 95 wt. % and preferably from about 30 to about 85 wt. %, whereas the organic solvent or solvent mixture is present in an amount from about 5 to about 30 wt. %.
The colorant, particularly when it is a hair colorant, can be in the form of an aqueous or aqueous-alcoholic solution, a cream, a gel, an emulsion or an aerosol foam. The hair colorant is packaged in the form of either a one-component preparation or a multicomponent preparation, for example in the form of a two-component preparation. In the latter case, the dye derivative of formula (I) is packaged separately from the other components, and the ready-for-use hair colorant is prepared only just before use by mixing the two components.
The colorant has a pH from about 3 to about 10 and preferably from about 4 to about 10. Both organic and inorganic acid and bases can be used for pH adjustment.
Suitable acids are, in particular, the following: xcex1-hydroxycarboxylic acids, for example glycolic acid, lactic acid, tartaric acid, citric acid or malic acid; ascorbic acid; gluconolactone; acetic acid; hydrochloric acid or phosphoric acid, as well as mixtures of said acids.
Suitable bases are, in particular, sodium carbonate, sodium hydrogen carbonate, potassium carbonate, potassium hydrogen carbonate, sodium phosphate, borax (Na2B4O7x10H2O), disodium hydrogen phosphate, alkanolamines, for example monoethanolamine or triethanolamine, ammonia, aminomethylpropanol and sodium hydroxide.
As a rule, the colorant is used by applying to the hair an amount sufficient for hair dyeing, namely about 30 to about 120 grams, depending on the length of the hair, allowing the colorant to act for about 1 to about 60 min, preferably 5 to 30 min, at about 15 to about 45xc2x0 C., then rinsing the hair thoroughly with water, optionally washing it with a shampoo and finally drying it.
The colorant described in the foregoing also contains natural or synthetic polymers or modified polymers of natural origin commonly used in cosmetic preparations so that the hair is fixed at the same time it is being colored. In general, such agents are referred to as shade fixatives or color fixatives.
Suitable among the known synthetic polymers used for this purpose in cosmetics are, for example, polyvinylpyrrolidone, polyvinyl acetate, polyvinyl alcohol or polyacrylic compounds such as polyacrylic acid, polymethacrylic acid, basic polymers of esters of polyacrylic acid or polymethacrylic acid and aminoalcohols, for example the salts or quaternized products thereof, polyacrylonitrile, polyvinyl acetates and the copolymers of such compounds, for example polyvinylpyrrolidone-vinyl acetate. Suitable natural polymers or modified natural polymers are, for example, chitosan (deacetylated chitin) or chitosan derivatives.
The aforesaid polymers can be contained in the colorant in amounts commonly used for such preparations, particularly in an amount from about 1 to about 5 wt. %. The pH of the shade fixative or color fixative is preferably from about 6 to about 9.
The colorant and the additional fixing are carried out in the usual manner by moistening the hair with the fixative, styling and setting the hair and then drying.
The colorants containing the 4-nitro-2,1,3-benzoxadiazole derivatives of general formula (I) impart to keratin fibers (particularly human hair) under gentle, skin-compatible conditions an outstanding, uniform, intense and long-lasting coloration that is highly resistant to shampooing, light and perspiration.
Because of their high resistance to oxidants, the 4-nitro-2,1,3-benzoxadiazole derivatives of general formula (I) can also be used in oxidative colorants based on oxidation dye precursors. The 4-nitro-2,1,3-benzoxadiazole derivatives of general formula (I) can also be used in brightening shades whereinxe2x80x94for purposes of brightening or improving the luster of the hair to be coloredxe2x80x94the direct dyes are used in combination with an oxidant.
The 4-nitro-2,1,3-benzoxadiazole derivatives of general formula (I) can be prepared by introducing substituents into 4-nitro-2,1,3-benzoxadiazoles of formula (II) [wherein Y denotes halogen or OCH3 or OCH2CH3, and R1 and R2 have the same meaning as in formula (I)] by means of amines, alcohols, phenols, thioalcohols or thiophenols. 
General methods of preparation are described in the literature, for example in E. German Patent 227 704; Journal fxc3xcr praktische Chemie 327 (3), pages 487-504 (1985); Analytical Chemistry 1982 (54), pages 939-942; Journal of the Chemical Society (B) 1968, pages 334-338 or Canadian Journal of Chemistry, vol. 75 (1997), pages 1240-1247.
The following examples illustrate the object of the invention in greater detail without limiting its scope.